1. Field of the Invention
The present invention relates to a music playing data fetch circuit for a personal computer, and in particular to an improved music playing data fetch circuit for a personal computer which is capable of reducing the operational time of an operating system of a personal computer by fetching a serial playing data of a music playing program, and reducing a chip size by transmitting and receiving a midi data by using only a receiving channel of a universal type asynchronous transceiver.
2. Discussion of Related Art
FIG. 1 illustrates a conventional sound card circuit for a personal computer using a music playing program.
As shown therein, the conventional sound card circuit includes a CODEC 10 for receiving a musical instrument device interface (MIDI) signal from a central processing unit (CPU) of a personal computer, converting the thusly received signal into a digital midi data, a tone Read Only Memory (ROM) 30 for storing a tone data, a sound Integrated Circuit (IC) 20 for generating and outputting a tone corresponding to the tone data inputted, a micro-program control unit 40 for performing a stored micro-program in accordance with a midi signal from the CODEC 10, a program ROM 50 for storing a program code which is used when performing a micro-program of the micro-program control unit 40, a random access memory (RAM) 60 for storing a data which is used for performing the micro-program, and a modulation IC 70 for generating a sound wave form which forms a sine wave form.
The operation of the conventional sound card circuit will now be explained with reference to FIG. 1.
First, when a midi signal for requesting to play "Do" in piano is inputted from the CPU of the personal computer, the CODEC 10 receives the signal, converts the signal into a digital midi data, and transmits to the micro-program control unit 40.
The micro-program control unit 40 performs a micro-program, and analyzes an inputted midi data.
A tone data corresponding to "Do" is outputted from the tone ROM 30, and a predetermined tone corresponding thereto is generated by controlling the sound IC 20, and a wave form corresponding thereto is formed by controlling the frequency modulation IC 70 and then the tone signal is transmitted to the CODEC 10.
The CODEC 10 converts the data corresponding to the tone and wave form generated by the micro-program control unit 40 into an analog signal.
The program code which is used at the time when the micro-program control unit 40 performs a microprogram is read from the program ROM 50, and the RAM 80 temporarily stores and outputs the data.
However, the conventional sound card circuit has a problem in that if each function of the system is performed by using sound card circuits, the chip size is made bulky.
In order to overcome the above-described problem, the micro-program control unit 40, the program ROM 50, the RAM 60, and the frequency modulation ID 70 are operated based on the software and the CPU of the personal computer.
Namely, since the CPU has a multi-task function for concurrently performing a music or a game such as a cake walk, it is possible to process a serial midi data based on the software.
Therefore, the CODEC 10, the sound card IC 20, and the tone ROM 30 are configured as shown in FIG. 1, and the functions of the remaining elements are performed based on the software.
However, in the conventional sound card circuit, since the serial playing data of the music playing program is fetched based on the software, the sound card circuit is operated much more dependently to the operating system of the personal computer. Therefore, there may be computer programs which are not operated under DOS, Windows 3.1, and Windows 95. In addition, the software should be independently programmed with respect to each controller of the system.